Method and apparatus for testing ceramic articles



Feb. 18, 1964 B. E. WISHON ETAL 3,121,323

METHOD AND APPARATUS FOR TESTING CERAMIC ARTICLES Filed Nov. 22, 1961 2 Sheets-Sheet 1 &

55m. 5 WW DAN/EL ES REARDO/V BY comma F. srock A 7' 7' ORA E VS Feb. 18. 1964 B. E. WISHON ETAL 3,121,323

METHOD AND APPARATUS FOR TESTING CERAMIC ARTICLES Filed Nov. 22, 1961 1 2 Sheets-Sheet 2 INVENTORS BER/ L E. WAS/ 0N DAN/EL E. REARDON BY DONALD F. STOCK ATTORNEYS United States Patent 3,121,323 METHUB AND APEARATUS FQR TESJNG CERAMK ARTHQLE Berhl E. Wishon, Daniel E. Boarders, and Donald F. Stock, Fittshurgh, Pa, 'assigners to Harbisen Wnlker Refractories Company, Pittsburgh, fi es, a corporation of Pennsylvania Filed Nov. 22, 1961, Ser. No. 154,134 2 Claims. ((1. 73-38) This invention relates to a method for determining the presence of flaws in hollow ceramic articles without destroying them, and more particularly for detecting cracks, holes and excessive porosity in refractory nozzles.

Ladles constructed of steel plates and lined with refractory brick are used for transferring molten steel from open hearth furnaces to locations where it can be teemed into ingot molds. To prevent slag, which may fioat on the steel in such a ladle, from entering the mold and contaminating the ingot, the steel is teemed through an open ing in the bottom of the ladle. That opening is lined with a tubular nozzle of suitable refractory material. For opening and closing the nozzle when moving the ladle from mold to mold, the ladle is equipped with a stopper that can be operated by the pouring operator on the teeming platform. The stopper commonly consists of a steel rod, protected by refractory sleeves, to the lower end of which is attached a head made of clay and graphite and fitting snugly into the upper end of the nozzle in the bottom of the ladle. The stopper acts as a valve to control the flow of metal out through the nozzle.

The size of the nozzle is determined largely by the capacity of the ladle and the thickness of its lining, but the length of the nozzle must be such as to produce a smooth, solid stream of metal as free from turbulence and spraying as possible. The refractories used in nozzle construction must withstand thermal shock and corrosion by molten steel and are generally made from fireclay. There are two reasons for using this type of refractory product, both based on the time factor. First, nozzles are used for only one heat and are seldom in use for more than an hour. Second, nozzles must become pyroplastic to function to best advantage; the surface of the upper end of the nozzle softening when in contact with molten steel and providing a soft, yielding seat for the harder stopper head, whereby a tight seal is formed. it will be understood that the nozzles should be dense enough to reduce orifice erosion, and must be free from cracks, holes and other flaws which would permit the molten steel to escape. Furthermore, such flaws can lead to the complete breakdown of the nozzle so that flow of molten steel from the ladle cannot be cut off by the stopper as the ladle is moved from one ingot mold to another. This situation creates a hazard in the shop and is wasteful of molten steel.

Even a single bad nozzle in a shipment may lead to the loss of a complete heat of steel. A shipment in which 99 percent of the nozzles are flawless is not good enough. Existing quality testing programs are set up on a statistical basis, with tests of only a few specimens providing data considered to be representative of an entire shipment of nozzles. That method has not furnished adequate safeguards, but it is the method in general use. To date, the most dependable test for steel pouring nozzles is the determination of porosity by boiling in water and the examination of a sawed cross-section to detect the presence of flaws. Unfortunately, they are destructive tests which render the tested samples useless. Furthermore, only by inference, proved by experience to be undependable, can it be assumed that the untested nozzles in the lot are as good as those tested.

It is an object of this invention to provide a nondestructive test which can be applied to every nozzle or other hollow ceramic article quickly, easily and economically, so that those with significant flaws can be rejected.

Other objects are to provide a testing method and apparatus which do not in any way impair the article being tested, which furnish a clear and definite indication of its quality in an accurate and uniform manner, and which does not require the exercise of judgment on the part of the operator.

The invention is illustrated in the accompanying drawings, in which FlG. l is a diagrammatic view of our apparatus; and

FIG. 2 is a fragmentary diagrammatic view showing a nozzle being tested.

Referring to the drawings, the vertical side members 1 and 2 of an upright frame are connected at the top by a cross member 3. A suitable distance below the cross member there is a platform 4 connecting the side members and serving as a support for the articles to be tested. Mounted on the top cross member is a vertical air cylinder 6 containing a piston 7 connected to the upper end of a piston rod 8 that extends down through the cross mem her and carries a clamping plate 9 on its lower end. Mounted on the platform directly below this plate is a cylindrical cup 11 containing a thick sealing gasket 12 provided with a downwardly tapered socket adapted to fit the tapered lower end of a permeable refractory nozzle 13 shown in FIG. 2. The center of the bottom of the cup has an opening 14 through it.

The opposite ends of air cylinder 6 are connected by pipes 16 and 17 with the opposite end portions of a fourway valve 18 of any suitable construction. The valve shown is an electrically operated double solenoid valve. The inlet of the valve is connected to an air-pressure line 19, in which there is a pressure reducing valve 2%. This line also is connected by a line 21 to one end of a flow meter 22. The second line 21 contains a normally closed solenoid valve 23 and a pressure regulator 24 set for a much lower pressure than reducing valve 24). The outlet of the flow meter is connected by a pipe 25 to opening 14- in the bottom of the nozzle-supporting cup.

It will be seen that after a nozzle has been set on the gasket in the cup, the nozzle can be clamped in place by lowering piston 7. Between plate 9 and the upper end of the nozzle, there is a sealing gasket 27 shaped to fit in the concave upper end of the nozzle. This gasket may be a separate element that is set on the nozzle, or it can be attached permanently to the bottom of the plate as shown. After the nozzle has been clamped in place, air is supplied to its lower end to establish a predetermined constant pressure in the nozzle. The rate of flow through the meter 2?. necessary thereafter to maintain that pressure establishes a permeability value for the nozzle, from which judgment as to whether or not the nozzle is too permeable for acceptance can be exercised. The reading will be infiuenced by holes and cracks in the nozzle, as well as by simply excessive porosity.

To operate the piston and to supply testing air to the chamber or passage inside of the nozzle, one solenoid 30 of the four-way valve 18 is connected by a wire 31 to a normally open push-button switch 32, and the other solenoid 33 is connected by a wire 34 to another push-button switch 35'. Both solenoids are connected by a common Wire 36 to a main circuit 37. Preferably, both switches are mounted close together on one side of the frame and are connected by a common wire 38 to a push-button switch 39 on the other side of the frame. This last switch is connected by a wire 40 to main circuit 37. By mounting switches in this manner at opposite sides of the frame, the operator must use both hands in order to actuate the piston, so there is no danger of his accidentally putting 3,1 3 his hand between plate 9 and the nozzle while the plate is being lowered.

When the left-hand switch 39 and the upper right-hand switch 32 are closed, valve 18 is shifted so that air pressure is delivered tothe upper end of the cylinder and the lower end of the cylinder is connected with exhaust. After plate 9 has been lowered to clamp the nozzle in place, the switches are released. As the upper gasket 27 becomes pressed again-st the nozzle with the desired force, the pressure in the upper end of the cylinder and in pipe 16 builds up to the point where it closes a normally open pressure switch 42 that is connected to the main circuit 37 by a wire 43 and to one side of solenoid valve 23 by Wire 44. The other side of the solenoid valve is connected to wire 36 by a Wire d5. Closing of the pressure switch therefore opens valve 23, and air is delivered to the closed chamber in the nozzle through its lower end. The pressure regulator 24 is adjusted to hold the pressure between it and the nozzle at a constant level of a few pounds; for example, 5 pounds, per square inch, and the flow meter will show how fast it is escaping from the nozzle. Since the nozzle is permeable, the air normally will escape slowly. If the flow meter shows a rate of flow higher than normal, the nozzle is defective and must be discarded.

After the test, the push button switches 39 and 35 are closed to reverse the four-Way valve 18 and thereby lift plate 9 from the top of the nozzle so that the latter can be removed from its support. The moment the valve was reversed, the pressure in the upper end of the cylinder was connected with atmosphere, so pressure switch 42 opened and allowed solenoid valve 23 to close and shut 0d the air supply to the nozzle.

The apparatus disclosed herein provides a rapid, simple and non-destructive test for the detection of flaws in hollow ceramic articles, particularly refractory nozzles that are used in ladles. A pair of workmen can test between 75 and 10 0 nozzles per hour with this apparatus. It also is readily adaptable to receiving and testing articles of other shapes having passages therethrough, or even having cavities extending only part way through. Of course, whether the test article is disposed vertically or horizontally depends simply on the locations of the clamping and sealing members in the apparatus.

According to the provisions of the patent statutes, we have explained the principle of our invention and have illustrated and described what we now consider to represent its best embodiment. However, We desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

We claim:

1. Permeability testing apparatus comprising (1) a perforated support member having a hollow cylindrical member disposed on the upper surface thereof and in alignment with the perforation in the support; (2) upstanding sidewalls extending from the outer periphery of the upper surface of the support and being connected at the upper end thereof by a perforated cross memv er; (3) a vertical air cylinder disposed on the upper end of the cross memi bet and in alignment with the perforation thereof, the air cylinder containing a movable piston therein connected to the upper end of a piston rod which extends, through the perfora ion in the cross member and has a clamping plate secured to the lower end thereof, the clamping plate when depressed and the hollow cylindrical member on the support cooperating to secure an open ended, hollow, permeable refractory member therebet-Ween and closing the open ends from the atmosphere; (4) means for supplying fluid pressure to the air cylinder to depress the piston and the interconnected clamping plate; (5) mean for supplying fluid under pressure to the perforation in the support, the perforation being open to the hollow in the refractory member; (6) a conduit connecting the supplying means with the opening through the hollow cylindrical member and the adjacent open end of the refractory member aligned therewith; (7) a normally closed solenoid valve in said conduit; (8) a normally open pressure switch electrically connected with the valve; (9) a PTESSlllfi regulator in the conduit; and (10) a flow meter in the conduit for measuring the rate of how of the fluid after it leaves the regulator.

2. Permeability testing apparatus comprising (1) a perforated support member having a perforated cupshaped member disposed on the upper surface thereof and in alignment with the perforation in the support, the cup-shaped member being suitable for closing one end of the passage through a permeable refractory nozzle; (2) upstanding sidewalls extending from the outer periphery of the upper surface of the support and being connected at the upper end thereof by a perforated cross member; (3) a movable piston disposed above the cross member being connected to the upper end of a piston rod which extends through the penforation in the cross member and has a clamping plate secured to the lower end thereof, the clamping plate being capable of engaging the opposite end of the nozzle for closing that end of the passage from the atmosphere; (4) fluid pressure actuated means for moving the piston toward and away from the cup-shaped member to clamp the nozzle between them, the opening in the cup-shaped member communicating with the nozzle passage; (5) means for supplying fluid under pressure to the perforation in the support; (6) a conduit connecting the supplying means with the perforated cup-shaped member and the aligned open end of the permeable refractory nozzle; (7) a normally closed solenoid valve in said conduit; (8) a normally open pressure switch electrically connected with the valve; (9) a pressure regulator in the conduit; and (10) a flow meter in the conduit for measuring the rate of flow of the fluid after it leaves the regulator.

References Qited in the file of this patent UNITED STATES PATENTS 182,397 Wood Sept. 19, 1876 1,473,963 Mills Nov. 13, 1923 2,157,135 Little et a1 May 9, 1939 2,480,665 Morgan Aug. 30, 1949 2,895,328 Payne July 21, 1959 2,919,573 Berkley et a1 Jan. 5, 1960 

1. PERMEABILITY TESTING APPARATUS COMPRISING (1) A PERFORATED SUPPORT MEMBER HAVING A HOLLOW CYLINDRICAL MEMBER DISPOSED ON THE UPPER SURFACE THEREOF AND IN ALIGNMENT WITH THE PERFORATION IN THE SUPPORT; (2) UPSTANDING SIDEWALLS EXTENDING FROM THE OUTER PERIPHERY OF THE UPPER SURFACE OF THE SUPPORT AND BEING CONNECTED AT THE UPPER END THEREOF BY A PERFORATED CROSS MEMBER; (3) A VERTICAL AIR CYLINDER DISPOSED ON THE UPPER END OF THE CROSS MEMBER AND IN ALIGNMENT WITH THE PERFORATION THEREOF, THE AIR CYLINDER CONTAINING A MOVABLE PISTON THEREIN CONNECTED TO THE UPPER END OF A PISTON ROD WHICH EXTENDS THROUGH THE PERFORATION IN THE CROSS MEMBER AND HAS A CLAMPING PLATE SECURED TO THE LOWER END THEREOF, THE CLAMPING PLATE WHEN DEPRESSED AND THE HOLLOW CYLINDRICAL MEMBER ON THE SUPPORT COOPERATING TO SECURE AN OPEN ENDED, HOLLOW, PERMEABLE REFACTORY MEMBER THEREBETWEEN AND CLOSING THE OPEN ENDS FROM THE ATMOSPHERE; (4) MEANS FOR SUPPLYING FLUID PRESSURE TO THE CYLINDER TO DEPRESS THE PISTON AND THE INTERCONNECTED CLAMPING PLATE; (5) MEANS FOR SUPPLYING FLUID UNDER PRESSURE TO THE PERFORATION IN THE SUPPORT, THE PERFORMATION BEING OPEN TO THE HOLLOW IN THE REFACTORY MEMBER; (6) A CONDUIT CONNECTING THE SUPPLYING MEANS WITH THE OPENING THROUGH THE HOLLOW CYLINDRICAL MEMBER AND THE ADJACENT OPEN END OF THE REFRACTORY MEMBER ALIGNED THEREWITH; (7) A NORMALLY CLOSED SOLENOID VALVE IN SAID CONDUIT; (8) A NORMALLY OPEN PRESSURE SWITCH ELECTRICALLY CONNECTED WITH THE VALVE; (9) A PRESSURE REGULATOR IN THE CONDUIT; AND (10) A FLOW METER IN THE CONDUIT FOR MEASURING THE RATE OF FLOW OF THE FLUID AFTER IT LEAVES THE REGULATOR. 